螺杆螺旋槽道内气液两相流流动特性的实验研究

发布时间：2018-03-14 13:19

本文选题：膨胀机　切入点：螺旋槽道　出处：《北京工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：单螺杆膨胀机是一种利用低温小规模热源进行发电的动力设备,可在较低温度热源下获得相对较高的发电效率,在余热回收利用工程中具有良好的应用前景。目前对单螺杆膨胀机的研究主要侧重在加工和性能方面,缺少对单螺杆膨胀机螺杆螺旋槽道内两相流流动特性的研究,而单螺杆膨胀机螺杆螺旋槽道内气液两相流的流动特性正是影响其工作效率的重要因素之一。因此,提出对螺杆螺旋槽道内气液两相流流动特性进行实验研究。实验中采用有机玻璃材质加工出直径分别为117mm、155mm两种尺寸的透明螺杆。螺杆中的螺旋槽道是一种截面形状不规则的三维螺旋槽道,实验以水和空气为工质对该螺杆螺旋槽道内气液两相流流动特性展开研究。借助高速摄像仪,采用背光成像的可视化方法对单螺杆螺旋槽道内流型结构进行观测,得到了不同工况条件下,不同周角位置处气液两相流型及各流型的特征。实验结果表明:螺杆螺旋槽道内主要存在泡状流、间歇流和环状流等流型;各流型的特征受工况条件和周角位置的影响而各不相同,即使同一工况下,同一流型在各周角位置的特征也不相同。根据实验观测结果,绘制了三个周角位置处的流型图,并对各流型之间的转换特性进行分析,给出了泡状流向间歇流转变、环状流向间歇流转变的准则关系式。由于气液两相流的压降和压差波动信息可以反映通道内两相流动的状况,研究这些参数的特性对实现两相流动监测与控制具有重要意义,对两相流动系统的设计和运行等问题也具有指导意义。因此,对螺杆螺旋槽道内气液两相流在进、出口处的压降进行实验研究,对不同流型时的压差波动信号进行统计分析,提取压差波动信号的概率密度函数特征和功率谱密度函数特征,为提高单螺杆膨胀机系统的运行效率提供基础指导。
[Abstract]:Single screw expander is a kind of power equipment which uses low temperature and small scale heat source to generate electricity, which can obtain relatively high power generation efficiency under lower temperature heat source. It has a good application prospect in waste heat recovery and utilization engineering. At present, the research on single screw expander is mainly focused on processing and performance, but the study on two-phase flow characteristics in screw groove of single screw expander is lacking. The flow characteristics of gas-liquid two-phase flow in the spiral channel of a single screw expander are one of the important factors affecting its working efficiency. The flow characteristics of gas-liquid two-phase flow in screw spiral channel were studied experimentally. In the experiment, transparent screw with diameter of 117mm / 155mm and diameter of 117mm / 155mm were fabricated by using organic glass material. The spiral groove in screw is a cross-section. Irregular three-dimensional spiral groove, The flow characteristics of gas-liquid two-phase flow in the spiral channel of the screw were studied with water and air as the working medium. The flow pattern of the spiral channel of the single screw was observed by means of high speed camera and visual method of backlight imaging. The characteristics of gas-liquid two-phase flow patterns and flow patterns at different circumferential angles are obtained under different working conditions. The experimental results show that there are mainly bubbly flow, intermittent flow and annular flow in screw screw spiral channel. The characteristics of each flow pattern are different from each other by the working conditions and the circumferential position. Even under the same working condition, the characteristics of the same flow pattern at each circumferential angle are different. According to the experimental observation results, the flow pattern at the three circumferential positions is plotted. The conversion characteristics between different flow patterns are analyzed, and the bubbly flow flow transition is given. Because the pressure drop and pressure fluctuation information of gas-liquid two-phase flow can reflect the condition of two-phase flow in the channel, it is important to study the characteristics of these parameters to realize the monitoring and control of two-phase flow. Therefore, the pressure drop at inlet and outlet of gas-liquid two-phase flow in screw spiral channel is studied experimentally, and the fluctuation signals of pressure difference in different flow patterns are analyzed statistically. The characteristics of probability density function and power spectrum density function of differential pressure fluctuation signal are extracted to provide basic guidance for improving the operation efficiency of single-screw expander system.
【学位授予单位】：北京工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O359.1;TK115

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